As is known in the art, the existence of foreign matter or objects on a radar such as an automotive radar sensor of the type described in U.S. Pat. No. 5,959,570, for example, can impact the accuracy and reliability of the radar. For example, the foreign matter or objects may undesirably block one or more portions of the radar sensor transmit and/or receive antennas and in particular may block portions of the RF energy propagating to and from the transmit and receive antennas of the radar sensor.
Such blockage may, for example, be the result of an accumulation, over a period of time, of foreign matter or objects in the region of an antenna aperture. Such foreign matter may be caused for example by environmental conditions such as temperature, humidity, ice, rain and the like. Such blockage can degrade, or in extreme cases even prevent, proper operation of the automotive radar sensor. If the foreign matter accumulates over time, there is a corresponding gradual decrease in sensor system performance over time. Since the accumulation is gradual, it is sometimes relatively difficult to detect the existence of antenna blockage due to the gradual accumulation of foreign matter and corresponding gradual decrease in radar sensor performance.
It would, therefore, be desirable to provide a radar which is capable of detecting blockage. It would also be desirable to provide a radar which is capable of detecting blockage due to the accumulation of foreign matter, such as mud, ice, snow or the like, on or proximate a radar radome. It would further be desirable to provide a radar which detects blockage and which notifies a system user of the existence of such blockage. It would be further desirable to provide an automotive radar sensor capable of detecting blockage. It would also be desirable to provide an automotive radar sensor which is capable of detecting blockage due to the accumulation of foreign matter, such as mud, ice, snow or the like, on the vehicle in or proximate that area of the vehicle in which the automotive sensor is mounted. It would further be desirable to provide an automotive radar sensor which detects blockage and which notifies a system user of the existence of such blockage.